Printing device comprising electro-magnets

ABSTRACT

Device for printing dots selected from series of dots arranged on a line, comprising a from a of separately energizable electromagnets having movable cores, the pulses of which are transferred to printing styli striking a printing surface. According to the invention said electro-magnets, arranged in a common cage parallel to each other in the direction of striking, have their cores prolonged by pushing members acting upon levers arranged substantially along radii from the striking zone, said levers bearing on the periphery of said cage and holding at their free ends said printing styli and exerting on said cores an elastic pressure in the direction towards their rest positions.

United States Patent [19] Milan Nov. 19, 1974 PRINTING DEVICE COMPRISINGELECTRO-MAGNETS [75] Inventor: Lucien Milan, Garches, France [73]Assignee: U.S. Phillips Corporation, New

York, N.Y.

[22] Filed: July 9, 1970 [21] Appl. No.: 53,418

[52] 11.8. CI 197/1 R [51] Int. Cl B41j 3/44 [58] Field of Search 197/1R; 101/93 C [56] References Cited UNITED STATES PATENTS 3,099,711 7/1963Foley et a1. 197/1 R X 3,209,681 10/1965 Sanborn 197/1 R X 3,243,0313/1966 Przysiecki 197/6.l 3,254,750 6/1966 Goldner 197/6.l 3,467,2329/1969 Paige 197/] R FOREIGN PATENTS OR APPLICATIONS 1,577,409 8/1969France 197/1 R 537,343 6/1941 Great Britain 197/1 R PrimaryExaminerRobert E. Pulfrey Assistant Examiner-R. T. Rader Attorney,Agent, or Firm-Frank R. Trifari 57 ABSTRACT Device for printing dotsselected from series of dots arranged on a line, comprising a from a ofseparately energizable electro-magnets having movable cores, the pulsesof which are transferred to printing styli striking a printing surface.

According to the invention said electro-magnets, arranged in a commoncage parallel to each other in the direction of striking, have theircores prolonged by pushing members acting upon levers arrangedsubstantially along radii from the striking zone, said levers bearing onthe periphery of said cage and holding at their free ends said printingstyli and exerting on said cores an elastic pressure in the directiontowards their rest positions.

1 Claim, 6 Drawing Figures PAIENIEL HH 3.848.719

SHEEI 1 OF 2 INVENTOR.

LUCIEN MiLAN AGENT PATENTELXJV 1 W4 3.848.719

SHEET 2 OF 2 INVENTOR. 1

LUCIEN MILAN 2 I l. C

AGENT PRINTING DEVICE COMPRISING ELECTRO-MAGNETS This invention relatesto a device for printing dots selected from a series of dots arranged inlines, said device comprising a set of separately energizableelectromagnets having movable cores, the pulses of which are transmittedto printing styli striking a printing surface.

Among the printing means employed, for example, as output members ofcomputers, termed printers, some of them print the characters in theform of dots. The dots are printed bymeans of printing styli inconsecutive, parallel lines or columns, while a series of styli arrangedin columns and selected by number and place for representing a portionof a character simultaneously receive a pulse. The characters may beformed by dots selected from the thirty five dots of a group of fivecolumns of seven dots each.

These printers must in the first place have a high printing rate,preferably with a minimum of volume. A known printing device (fromFrench Patent Specification No. 1,405,348) uses a series ofelectro-magnets energized selectively, the movable cores of which areprolonged by flexible wires, the ends of which serve as printing styli.Such a device, though working at a comparatively high rate, has anon-negligible volume and its reliability is limited by wear of saidflexible wires in their guides. The device is highly exposed to externalinfluences. Moreover, the various wires of the same set do not cover thesame trajectories and the stroke of the printing styli is not perfectlyhomogeneous.

The present invention has for its object to provide a printing devicecomprising electro-magnets and printing styli, whose printing rate ishigher than that of the aforesaid devices, the reliability beingimproved, the volume being reduced, the stroke being homogeneous and theprotection from external influences being improved.

According to the invention the device is characterized in that saidelectro-magnets arranged in a common cage parallel to each other in thedirection of striking, have their cores prolonged by pushing membersacting upon levers arranged substantially along radii from the strikingzone and bearing on the periphery of said cage and holding at their freeends said printing styli and exerting on said cores an elastic pressurein the direction to their rest positions.

In an advantageous embodiment of the invention the working point of saidpushing member is located substantially at equal distances from thestylus and from the fulcrum of each lever.

In a further preferred embodiment of the invention the cage in which theelectro-magnets are accommodated is cylindrical, whilst theelectro-magnets are arranged in a circle.

In a still further preferred embodiment of the invention the levers areformed by elastic rods rigidly held at one end, the other end being bentover at right angles in the form of a printing stylus.

In a further preferred embodiment the levers are formed by tonguespunched from an elastic, flat disc fixed to the periphery of said cageand pointing towards the centre of the cage, the end of each tonguebeing provided with a printing stylus.

In a further preferred embodiment of the invention the levers are rigidand pivotable at their fulcrum, each of said levers co-operating with aspring the force of which acts opposite the pulses of saidelectro-magnets.

The following description given with reference to the accompanyingdrawings will show how the invention may be carried into effect.

FIG. 1 is a perspective view of a device in accordance with theinvention.

FIG. 2 is a sectional view taken on the line B-B in FIG. 3 of a devicein accordance with the invention in a first embodiment.

FIG. 3 is a cross sectional view taken on the line A-A in FIG. 2 of thesame device.

FIG. 4 is a sectional view taken on the line CC in FIG. 5 of a device inaccordance with the invention in a second embodiment.

FIG. 5 is a front view of the device shown in FIG. 4.

FIG. 6 is a partial sectional view taken on the axis of the drum of adevice in accordance with the invention in a third embodiment.

The device shown in FIG. 1 is accommodated in a cage 1 closed by a lid2, secured, for example, by screws 5. The lid 2 is pierced by a gap 3through which printing styli 4 are passed.

In FIG. 1 the number of printing styli amounts to seven. Two of them areshown in the striking position. These styli are formed by rigid rodsarranged in parallel closely adjacent each other: the gap 3 guides themin common. From FIG. 1 it will be seen that the device according to theinvention ensures complete protection of the movable elements therein:the electro-magnets, the levers, the styli, against external influences.

These movable elements are shown in the sectional views of FIGS. 2 and3; they are circular arranged'in the cylindrical cage 1 made of magneticmaterial preferably having high permeability. This circular disposition, which can be carried out in a simple manner, facilitates themanufacture of a high-precision device. In the cells 6 of the cage 1 areaccommodated the coils 7, along the axes of which the magnetic cores 8are adapted to move. These cores 8 are prolonged by pushing rods 9 ofnon-magnetic material, guided in rings 10 which complete the magneticcircuits.

The pushing rods 9 act each on an elastic rod 11, which is held at 12between the cage 1 and its lid 2 and bent over substantially at rightangles at 13 in order to form a printing stylus such as 4. The materialand the section of these rods ensure a sufficient elasticity forresetting the cores of the electromagnets and for holding them in therest position. This embodiment is conspicuous by its great simplicityand reduced cost offabrication. The reliability of the device isguaranteed by the simplicity of the parts. Frictions are minimized andwear is negligible.

FIGS. 1 to 3 show a device comprising seven printing styli, but as amatter of course an identical embodiment may be made for devicescomprising a different number of styli.

The ends of the rods 11 forming the printing styli are flush with thesurface of the lid 2 in their rest position. This position is determinedby a stop at which each electro-magnet is returned by the elasticpressure of the corresponding rod 11; this stop is formed in this caseby a washer or circlip l4 bearing on the ring 10' and being arranged oneach pushing rod 9.

A cap 15 protects the rear side of the device. This cap may furthermorehold the output connections of the windings 7.

The arrangement of the group of electro-magnets of the device accordingto the invention occupies a minimum space, since the electro-magnets aredisposed parallel to each other.

The action of the pushing members on the printing styli via leversprovides, with the same track of the styli, a reduction of the tracks ofthe electro-magnets. This reduction corresponds to an equivalentreduction of the gap of the electro-magnets in the rest position so thatthe response time is shorter, the flyback time may be shorter and with agiven type of electro-magnet the force may be higher. The risks ofbouncing and vibrations are reduced.

In the variation shown in FIGS. 4 and 5 the rods 11 of the devicedescribed above are replaced by tongues 24 punched from a washer 20,which is held at its periphery between the drum 21 and a lid 22 securedby screws 19. The lid 22 has a passage 23 for the desired number ofaligned styli, in this embodiment nine. The elastic tongues 24 pointtowards the axis of the device, each tongue having secured to it, forexample, by electric welding at 27, a bent-over rod 25 to form aprinting stylus at 26.

This embodiment, exhibiting a great simplicity, permits the use ofdifferent materials for the levers and for the printing styli so as tomatch their individual functions perfectly. This embodiment provides, inaddition, the other advantages of the aforementioned embodiment.

The printing pulses are imparted to the styli by means of theelectro-magnets described with reference to FIGS. 2 and 3, comprising acoil 28, a movable core 29, a pushing member 30, an abuttment washer 31,a guiding ring 32 of magnetic material. The external magnetic circuit ofeach electro-magnet is formed by a hollow cylinder 33 of magneticmaterial. The cylinders 33 are mounted in the cage of the drum 21, madein this case of non-magnetic material. Plugs 34 complete the protectionof the device.

The body of the drum 21 comprises an eccentric portion 35 provided withcushions 36 serving as guide members along a bar 37 and bearing on aslide 38, while the body of the cage 21 thus forms a styli holdingcarriage, which is adapted to perform translatory movements at rightangles to the line of dots which the device is capable of printing, thecarriage being pivotable about the bar 37.

The partial view of FIG. 6 shows a variation of an embodiment of theinvention, in which the levers are rigid and elastic resetting means ofthe electro-magnets act on said levers, for example coil springs.

The electro-magnets are circular arranged in a cage 41 as describedabove. The cage 41 is closed by a lid 42, having a passage 43 for theprinting styli. The latter are formed by bent-over rods 44, which arefixed, for example by electric welding at 49, to levers 45, formed byrigid flat strips pivotable on shafts 46. The cage 41 is provided withgaps 47 for passing the levers 45. The pushing members 48 of theelectro-magnets act upon a point of the levers located between thewelding point 49 and the shaft 46. The point of co-operation between thepushing members and the levers is preferably chosen at substantiallyequal distances from the printing styli and the supporting point of eachlever. In this case the effective travel of an electro-magnet is equalto half that of the stylus and the striking rate of the device may beincreased in the same proportion as compared with a device in which thetravel of an electromagnet is equal to that of the stylus actuatedthereby. A spring 50 acting against the pushing member 48 urges eachlever against its pushing member and maintains each electro-magnet atthe stop in the rest position. The spring 50 may be a coil spring asshown in FIG. 6, but it may alternatively be formed by a leaf spring orany other kind of spring.

A printing device in accordance with the invention intended to printlines of seven dots spaced apart by 0.4 mm by means of styli of adiameter of 0.3 mm to form characters of a height of 2.5 mms iscompletely arranged in a cylinder of a diameter of 35 mms and a totallength of 45 mms. The track corresponding to the movement of a stylus is0.4 to 0.7 mm according to the printing surface technique and the trackof the corresponding electro-magnet is 0.2 to 0.35 mm. Under theseconditions a pulse of overall duration of less than 0.8 msec isnecessary to obtain a sufficient printing contrast. If the minimum timeinterval between two pulses can be reduced to 0.4 msec, for example,which permits the use of given moving techniques of the printingcarriage, the resultant rate is of the order of characters per second.

In the various embodiments described above the cage may be made eitherof non-magnet material, there being provided as many cells as there areelectromagnets to be held in each of them, or from a material havingsatisfactory magnetic permeability, the cage itself forming part of themagnetic circuits of the various electro-magnets held therein.

In order to print characters and lines of characters the deviceaccording to the invention may, as usual, be mounted on a carriageadapted to perform a translatory movement and, if desired, is tilted.

In a further mounting method the cage itself forms said carriage, whichis provided with the required guiding means.

What is claimed is:

1. A device for printing dots selected from a series arranged in a line,comprising a plurality of separately energizable elongatedelectro-magnets having parallel longitudinal axes arranged in a circle,a cylindrical enclosure surrounding the plurality of electro-magnets,each electro-magnet having an axial movable core, a plurality ofL-shaped printing levers substantially radially arranged within theenclosure, each printing lever having one end attached to the enclosureand having an opposite end arranged within a line formed by saidopposite ends, and a plurality of pushing members at tached to the coresof the electro-magnets, each pushing member aligned with a correspondingprinting lever, the printing levers exerting a biasing force on thepushing members in a direction corresponding to the rest position of thecores, said levers being formed by tongues punched from an elastic, flatdisc fixed to the periphery of said cylindrical enclosure and pointinginwardly into the cylindrical enclosure, the end of each tongue beingprovided with a printing stylus.

$232? UNHTED STATES PATENT OFFICE CERTIFICATE OF CORRECTION,

Rqtent No. 38%8719 Dated ovember 19, 1974 Inventor(s) Lucien Milan It iscertified that error appears in the above-identified patent and thatsaid Letters Patent are hereby corrected as shown below:

Under the Abstract, line 2, "a from a" should read a set of Signed andsealed this 18th day-of February 1975.

(SEAL) Attest:

c. MARSHALL DANN RUTH c. MASON- Arresting Officer Commissioner ofPatents and Trademarks

1. A device for printing dots selected from a series arranged in a line,comprising a plurality of separately energizable elongatedelectro-magnets having parallel longitudinal axes arranged in a circle,a cylindrical enclosure surrounding the plurality of electro-magnets,each electro-magnet having an axial movable core, a plurality ofL-shaped printing levers substantially radially arranged within theenclosure, each printing lever having one end attached to the enclosureand having an opposite end arranged within a line formed by saidopposite ends, and a plurality of pushing members attached to the coresof the electro-magnets, each pushing member aligned with a correspondingprinting lever, the printing levers exerting a biasing force on thepushing members in a direction corresponding to the rest position of thecores, said levers being formed by tongues punched from an elastic, flatdisc fixed to the periphery of said cylindrical enclosure and pointinginwardly into the cylindrical enclosure, the end of each tongue beingprovided with a printing stylus.